free the signature in do_strip_DER_encoding_from_ECSIG
free the signature in do_strip_DER_encoding_from_ECSIG

We do not need it around since we copy out the data
to the passed in data pointer.

also, do not double free the BIGNUMs in the error path
since those are free'd by ECDSA_SIG_free().

Yubico/yubico-piv-tool,Yubico/yubico-piv-tool,Yubico/yubico-piv-tool